SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e69673ee0dd88398904a2002578d37b7f1b0e7f55aa3c0d9054e2da7d44ded07' 
  AND token = 'YyFAKgg8XJHEWj9Tm1rIuEun83DNnm+8DWiHm+EfIao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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