SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9c14d6e9e8811b30102ad9693c2e907fd4f8d589ff3b0e424e0727b1aa835bf' 
  AND token = 'eATTSG4ZapmB5NvDU81SIIZwztkOHf3W2EcdUVrXFaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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