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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2b246b1e7db2b8961035ef2bea09bb38f7c5361bc1cf9ab9301901387e8fd35' 
  AND token = 'CNbH1CmQ2R1Gnr5Ix0WH2Nw8BpoLCP+FmQv9dE1/mnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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