SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f79c014eadaa29abed3d44f78e40874df0ecdd4835926e925d51d3e0536db5d8' 
  AND token = 'kVKJWIhuETDIWxkTGKEAU3STVwv5a6RI+D1UZXCBmt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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