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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8188e899fa8e3e6e2dfc8e653d6c6805d61a9aeed73c697c25a2490a42a0f196' 
  AND token = 'qt4wUApvrKxFY/JDicmaNJp5AVH3X9JHb1eCqc8Ip1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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