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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f65e4c63b517b1345ef4580f9468fbdbc41e574092e8b1de9b2c75e7e90e1a' 
  AND token = 'nupaxDujKttD+oIMS+IVL9IlJXAJr2a6Pyf7bKq/oCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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