SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b286487d6449d7d7461b3317d3e688a507ad37213b2d92e028b16dd7bc71dd30' 
  AND token = 'bKkwdhSkUdTtTxEW55AFCHeVoIeIghTzROXb8RZfKeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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