SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66df9bc5ab4ef0416fc6b70e86edb9d5b144bd9ac9ea60c4361f7d15a2472a21' 
  AND token = 'MD0Da6YquSAmKIP/KfEQwjX9mqBibom1YJWViFDSl5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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