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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9a457c037e4d5e52c2bcdb98c4efb5e83e2b1d3b8b55057a233b6efced23a58' 
  AND token = 'VWx1rb6zc9FwfI40hcAzWX5ars9ciHpWvhbTMRtOsqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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