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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8b967c755b243a5c7476e0f0d8b79ad7f70aa3d5d2435e356e40794a3d1747a' 
  AND token = 'dQB9QTzDfGwPYV1MDNP5cmS324MOE6dXLvBQeqnIh58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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