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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb6e63d96c85908159bdee97d28f6ef58a38e01ed6dfdc6b5ec5bc0c92c2339' 
  AND token = 'rUInU0k4JN1NXMSSCIHunecY3Fxpfhu+YFnYcqnRj1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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