SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcfe253652976fc1061502bfdbf579741b24227474d139333276dcafa3693648' 
  AND token = 'pGnSs/htZ1TXIlDAwB2R7bS8IhimIvlJwWeFJWBPqGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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