SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a574c7ff3b9c1aff1f740ab3251f585bcf66e957959e49b4acc46c35ea5be9a' 
  AND token = 'jYXLPvSLdDl2Z/9q1Rgrz3AlHVKWGrlHeC6aMqQy+HM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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