SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc1bb0576a0e56d27e2021b29d942ced8ffddbcce8ff2c3453bf18843e8152a9' 
  AND token = 'YRlnhmM+Ny2rgsBKwUlMcjXOWYa8hYGSqePn86tBiTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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