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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4f36085b528cbd38d6c3e4e2dd7847174e7135defb84e7caed8bc8312a360a4' 
  AND token = 'iw55jdidvx+ZqJlLyV7lZiZL2eDmcjoJH+8z4dwOWf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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