SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2c6cb875399bd7ef2d57b5d096b35d675183d27d58991276401be99e3052cf6' 
  AND token = '9rsqG72H8guh29lQ2fQhoSdGHojlgAsXnFPn8DYZAbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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