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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '294e30a0352b0951487f29b6a8a4743ae813086e912585b00c01967c896fbaba' 
  AND token = '/uiojcExz/IM8bI0c0O41ErAeqLlIBF0maC31R13f14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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