SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f2cbcc4ba511bb41fb6f2b362c003395f1a989c687720a6a9fad07411a7a1e' 
  AND token = 'AGUD4fIBmXZcg1Z+8H7Ia+MceA6w+576HNb6W2rTZ9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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