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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c2c2893e76318b0b6938a00105b189d5d4ae48b1aa9e5a24b6e6b26aeddb14c' 
  AND token = 'SMRf2S0oR/vQMIQg4zD4G1AsiONOMv26Pt9H+VJZcpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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