SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6cdbd18bb5dee70ec78ea4c3eba1ae1b4f89975effce8ec6d5661148b3e51be' 
  AND token = '7kVzPZm9Bgi40t3lazozOJMc46P4tgQ+gppe0EznQso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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