SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8292daae793692b0d4a3d34867e3bb1c4d6d00ee1899a38346a644ef30642c1' 
  AND token = 'AWfnnxPy1MgAVwYrdTuJCWAdHW3AOe9P4JNdmIkHFtQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}