SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eab18b10b0cc804a03b30eddedd7cab1a49bea09e074bca2084a7fbb2810342' 
  AND token = '+9C5EPcR0pKnsGBimSZ7fbGWpXCdTk/23jB6jlnNOJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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