SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb8c2e6e0a9aef44260a8245adff026821d0c61a312258811c7292e299615e21' 
  AND token = 'miEqC1CV6DagNdrYHXbVSKf0r4PaS0fCrC3HD+pYk/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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