SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70fdecd429750b3ebfe72d05b2e646c8519426c50c34a019496389a543855a91' 
  AND token = '0bwY+0c+aIvhoLiABzApYf1f8cICaEBjLZIKUniOIHE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}