SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239ebed27762318836e0e99d0d7c8efdf5423966b4624a4ed32e84a38ca5b637' 
  AND token = 'y3uYymDtLkUlR9TEF05Owfm1czCg5EAGltL2ToWTZnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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