SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd54e4687fdbffd9f5a1e7d0764ffcedc7fb4656a315b23bc936c1fe1138b3521' 
  AND token = 'JigZ2IfvHlZvSBSmkXOP9XOgjpIK3/ve14AYhfpqK7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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