SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b55f50a9340baf3dda321b2b3f10151f2c9088cd1b4c55206b46ad1d2dd63f9' 
  AND token = 'C2GPuG2Q0XEjQJKRDnIOmKLJZdBQVgY4fsqn/Y1vCjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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