SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '631ad23bec9774a92191d8ff1b054372d2fa1a13b14ae6cb7ca1dc80cff26562' 
  AND token = 'R4BujL9+CYHMvfCVNFwvYmGXNy2cdAXNJ+sK9IyoBMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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