SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51e5926a8a6db53267e4134bc73d97f57673f6987391de4663d4be95b37d94e5' 
  AND token = 'jWKT0TVwM4mhnq/DE7vGAJDHHsF5cmgT/WCAncitL7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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