SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f687147660f55cf5139a6f45e51340447cf75d3a5d3658aaf7b2ee5fa889ed3e' 
  AND token = 'pHgJvouuBMP++FrJZ/LepU7gOz/fKflkR+fO/Xlz4AI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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