SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b9604b1511d0982c56ddb223f0aa25615b0935f957fc6a31564c40bdd3f04d' 
  AND token = 'BeUmGMkS33ykEVYhbLvAfj90AvC1+P1MO3aEorWq6yA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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