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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7ebbebcab9408dc923eabffb0831319210f95a1613aad7734bc3d2cd7a2a1bd6' 
  AND token = 'KL7JgWyDvCLNjLDtzHxZjDk9OAGdu0zzFZmdZNQ/7RA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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