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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6c3935bda5930059e2f9a997b9eb2e910f116d72e34c76e259d98a61db43f2b4' 
  AND token = 't6bMiDr4xkW6trCXrGMuzciyCwutnkMVRzNmVLpux5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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