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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f66c891b3bd4aa0d91d584ddf9209b1e2a25b2512c81545f59ee1977b1ee8b6e' 
  AND token = 'kd4pDTsdrLvGcIT/JwvTLYOiFn5ygXvYYNnLRAty1E0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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