SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51fb8bcfd20101e886a3f2be88d9f0bd5927b987b3f039e9b657485318f2347' 
  AND token = 'g9BWZVdntMl+Z3k+hlhgRraOBRjBjXsR1/btyBuaJQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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