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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8126ef7e691c3081aa104f15c91e1105c0971a0736f742b2af6fb8ba56a193df' 
  AND token = 'dfu6+fYjx4ZzVkdopJNYdH2LSTKi0T1DSFj42ytQ5UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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