SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7758680fcedebab6a4180a9b937ac70773ac0551ea771d990c252936dff928a' 
  AND token = 'aKl5wMlhojq4nZE+KUapztp7SN1q/kHnHvx2roYkDWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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