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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b30317173f763ca00200f5d5880a9da30a3d29f3cccc15e6c0df3b21c4671d3a' 
  AND token = 'UFJs5VFGLHiTmsFEZ7CKX/3xVaxLmezMJZ5PFC/Ju0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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