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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b39d5130f2aa49d99f8db475927530fba9fcae611ebbdd6a81e7073113d5ea' 
  AND token = 'CExkztN3jRkNUs5076NXSbkvB+ok/RTtEovMa2g8dcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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