SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3570379c6124c5a94f27f05149e4fe87da2046688f9776fadfe34ebf959883f5' 
  AND token = 'DqdmXNi+ex1YxrBVlIlTeYACDNFlM679pkdFaPq4mss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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