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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a21b4ae81ab2a0f2701d2c42ac2064d16cebd2a2fc31495b343558d064f2bb23' 
  AND token = 'izyxXnQ8dGfBeYw9GVYY3bdTcubEElNqSF/axYCJUPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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