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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e6261e369d64c89d51b19e388fbf5fec181c39ecff9808ff50c0c2b7e1c4f9a7' 
  AND token = 'ZskNnih1JV3nb1nFKeZa5bWEBUnImf6K8q/U0V/wCMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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