SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91133b51798df1afb1f1290c40ac36a3ed0365681c5b0549fd2b7f439ff6e04' 
  AND token = 'fmOLWycTtu3/k+4vxekxJF6IXOwFZNY77ILRYtf1cyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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