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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '915a017b1282e3e53bfafa104bdc3ec9ee29d39f1403a3435e7cec989f10726c' 
  AND token = '+pk7dVENyILGpe6++FICyvvStvmIR4zGM50TGrbf4f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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