SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d0436ee56e6ccacaa660edc198fb160b450dd54d01c6f814c2f0d1bbcd24414' 
  AND token = 'rCXL/bPsYSbUkDg05hXMBk08PbXjtSefN65lQEfDquE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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