SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727383b2b80d33f89e403007442b479a37af4d09e5d4dae3f44285cfc405bd1e' 
  AND token = '8J1Brkz7PdAODjWLTYtUBu03mXhdG5XmwnfKsKP3sR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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