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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3e3d0f719e5ec35bd13cfc74dc459b7e9d47102b91ce7a962f775d04f34a267' 
  AND token = '0QKTfM0jJjtUJDnLhLggjbw1kEZsQdEsP7Kb3+3+Ojk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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