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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c40b45042d08c5f1d9ad8ac8e45520d0d550e06c8e2ea2adcac7c3ee48d2339f' 
  AND token = 'heS5aP7RMFrBpif8e3WoxYFvFkTHE/Q291oy7Lzmmzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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