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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bef5bdc2a8aeeb96ccf39b3f557357c3c66e3aa975c0eed7fef1b0b6de07d624' 
  AND token = 'L7/JnNkiwYJVeLtt+bRWTUbQg770qADrOuvd5KcXEJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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