SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a27971f346a580a28ce0961ae6e9a749ad4000df81e96d9f98323a7ae33ef210' 
  AND token = 'JifaRhmpR3CEvHaaRImkftVPGoZ+WhJdU2KOtHyrOhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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