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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2b271ccec35da1737dd39a4c0b1d6b18071133ca7f33da1698cd7a1b4bf9e238' 
  AND token = 'YDeI3KX2cIpvVkhCxhQeJ+zZ9VXbC7NLVUyTJ5EQtkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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