SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5321e0cbe44214c62d2d3702b71868658142d0cdcf59aed616229f6dbdad9e3' 
  AND token = 'K3R7YH1inZC/HRCGMfm/p6RzXxwhqlLERCZ3ZtejBEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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