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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e7f766d6b3039ea90af281c52d5a05d0186fb99d8740c8ea193ae4486d5ae7' 
  AND token = 'UGIMMNCDSs6QAaUs31dWjWuxm+CravM7x6fq0uMkB3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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