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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55e4c859870a8282be3e0ea9ad01c91570945d1f4fdfcbc4f1dfae5274f401ac' 
  AND token = 'Wnlm4Gkw6iGxrGUjZYMRDl+bKzpj7kxOMijSnoBUrBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}